1 /**
2 * eCryptfs: Linux filesystem encryption layer
3 *
4 * Copyright (C) 1997-2003 Erez Zadok
5 * Copyright (C) 2001-2003 Stony Brook University
6 * Copyright (C) 2004-2006 International Business Machines Corp.
7 * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
8 * Michael C. Thompson <mcthomps@us.ibm.com>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation; either version 2 of the
13 * License, or (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
23 * 02111-1307, USA.
24 */
25
26 #include <linux/fs.h>
27 #include <linux/mount.h>
28 #include <linux/key.h>
29 #include <linux/slab.h>
30 #include <linux/seq_file.h>
31 #include <linux/file.h>
32 #include <linux/statfs.h>
33 #include <linux/magic.h>
34 #include "ecryptfs_kernel.h"
35
36 struct kmem_cache *ecryptfs_inode_info_cache;
37
38 /**
39 * ecryptfs_alloc_inode - allocate an ecryptfs inode
40 * @sb: Pointer to the ecryptfs super block
41 *
42 * Called to bring an inode into existence.
43 *
44 * Only handle allocation, setting up structures should be done in
45 * ecryptfs_read_inode. This is because the kernel, between now and
46 * then, will 0 out the private data pointer.
47 *
48 * Returns a pointer to a newly allocated inode, NULL otherwise
49 */
ecryptfs_alloc_inode(struct super_block * sb)50 static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
51 {
52 struct ecryptfs_inode_info *inode_info;
53 struct inode *inode = NULL;
54
55 inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL);
56 if (unlikely(!inode_info))
57 goto out;
58 if (ecryptfs_init_crypt_stat(&inode_info->crypt_stat)) {
59 kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
60 goto out;
61 }
62 mutex_init(&inode_info->lower_file_mutex);
63 atomic_set(&inode_info->lower_file_count, 0);
64 inode_info->lower_file = NULL;
65 inode = &inode_info->vfs_inode;
66 out:
67 return inode;
68 }
69
ecryptfs_i_callback(struct rcu_head * head)70 static void ecryptfs_i_callback(struct rcu_head *head)
71 {
72 struct inode *inode = container_of(head, struct inode, i_rcu);
73 struct ecryptfs_inode_info *inode_info;
74 inode_info = ecryptfs_inode_to_private(inode);
75
76 kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
77 }
78
79 /**
80 * ecryptfs_destroy_inode
81 * @inode: The ecryptfs inode
82 *
83 * This is used during the final destruction of the inode. All
84 * allocation of memory related to the inode, including allocated
85 * memory in the crypt_stat struct, will be released here.
86 * There should be no chance that this deallocation will be missed.
87 */
ecryptfs_destroy_inode(struct inode * inode)88 static void ecryptfs_destroy_inode(struct inode *inode)
89 {
90 struct ecryptfs_inode_info *inode_info;
91
92 inode_info = ecryptfs_inode_to_private(inode);
93 BUG_ON(inode_info->lower_file);
94 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
95 call_rcu(&inode->i_rcu, ecryptfs_i_callback);
96 }
97
98 /**
99 * ecryptfs_statfs
100 * @sb: The ecryptfs super block
101 * @buf: The struct kstatfs to fill in with stats
102 *
103 * Get the filesystem statistics. Currently, we let this pass right through
104 * to the lower filesystem and take no action ourselves.
105 */
ecryptfs_statfs(struct dentry * dentry,struct kstatfs * buf)106 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
107 {
108 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
109 int rc;
110
111 if (!lower_dentry->d_sb->s_op->statfs)
112 return -ENOSYS;
113
114 rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
115 if (rc)
116 return rc;
117
118 buf->f_type = ECRYPTFS_SUPER_MAGIC;
119 rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen,
120 &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat);
121
122 return rc;
123 }
124
125 /**
126 * ecryptfs_evict_inode
127 * @inode - The ecryptfs inode
128 *
129 * Called by iput() when the inode reference count reached zero
130 * and the inode is not hashed anywhere. Used to clear anything
131 * that needs to be, before the inode is completely destroyed and put
132 * on the inode free list. We use this to drop out reference to the
133 * lower inode.
134 */
ecryptfs_evict_inode(struct inode * inode)135 static void ecryptfs_evict_inode(struct inode *inode)
136 {
137 truncate_inode_pages_final(&inode->i_data);
138 clear_inode(inode);
139 iput(ecryptfs_inode_to_lower(inode));
140 }
141
142 /**
143 * ecryptfs_show_options
144 *
145 * Prints the mount options for a given superblock.
146 * Returns zero; does not fail.
147 */
ecryptfs_show_options(struct seq_file * m,struct dentry * root)148 static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
149 {
150 struct super_block *sb = root->d_sb;
151 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
152 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
153 struct ecryptfs_global_auth_tok *walker;
154
155 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
156 list_for_each_entry(walker,
157 &mount_crypt_stat->global_auth_tok_list,
158 mount_crypt_stat_list) {
159 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
160 seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
161 else
162 seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
163 }
164 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
165
166 seq_printf(m, ",ecryptfs_cipher=%s",
167 mount_crypt_stat->global_default_cipher_name);
168
169 if (mount_crypt_stat->global_default_cipher_key_size)
170 seq_printf(m, ",ecryptfs_key_bytes=%zd",
171 mount_crypt_stat->global_default_cipher_key_size);
172 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
173 seq_printf(m, ",ecryptfs_passthrough");
174 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
175 seq_printf(m, ",ecryptfs_xattr_metadata");
176 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
177 seq_printf(m, ",ecryptfs_encrypted_view");
178 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
179 seq_printf(m, ",ecryptfs_unlink_sigs");
180 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
181 seq_printf(m, ",ecryptfs_mount_auth_tok_only");
182
183 return 0;
184 }
185
186 const struct super_operations ecryptfs_sops = {
187 .alloc_inode = ecryptfs_alloc_inode,
188 .destroy_inode = ecryptfs_destroy_inode,
189 .statfs = ecryptfs_statfs,
190 .remount_fs = NULL,
191 .evict_inode = ecryptfs_evict_inode,
192 .show_options = ecryptfs_show_options
193 };
194